Every year at Dragon*Con in Atlanta, GA,
they host two robot combat events. On Sunday,
it’s Robot Micro Battles, with one and three
pound robots facing off. On Monday, it’s Robot
Battles ( http://robotbattles.com) where the 12
and 30 pound robots fight. For the large robots,
the event takes place on an open stage with
weapon limitations for audience safety. The small
robots, however, fight in a full arena.

During Robot Micro Battles in 2011, the arena
was damaged and would need to be repaired if it
was to be used again. Instead of repairing the old
arena, it was decided that a new better one
would be made.

With the event taking place in a hotel during
a massive convention, there are a few unique
issues that come up. First, you need to be able to
quickly unload the arena to avoid being parked
too long in the loading zone near the hotel that
hosts the event. Second — with limited time before
and after the event to perform setup and
teardown — it must be quick to assemble. Third,
as there is no money coming in via registration
fees, costs must be kept low to minimize the
financial pain of the build and any repair costs.

These issues guided the direction of the build
and helped to produce a unique arena that can be
put together in an astoundingly short amount of
time.

The build team for the arena had a wide range of
skills that allowed the tasks to be split for increased
efficiency. During the initial stage of the build, half the
team worked on the wood portions of the structure
while the other half focused on the metalworking
portion of the build.

One of the guiding principles for the entire build
was “Use the least amount of threaded fasteners
possible for non-permanent connections” which means
many of the components in some way slot or slide
together, and are aided by spring clamps and pinned
connections. The legs of the arena are 4x4s with a
cutout at the top for the roof and a few pieces of 1x4
near the lower portion of the leg to align and support
the floor sections.

The floor and roof are assembled perpendicular to
one another to minimize arena bowing. There are also
four support legs under the arena floor along the center

FIGURE 1. A large portion of the metal used
for the arena build.

seam to provide additional support. During each major
stage of the build, we performed test fits to ensure that
the manufacturing tolerances weren’t causing assembly
issues.

One issue with the old arena was the short barriers
between the robots and the expensive 1/4 inch
polycarbonate walls which led to some cracked
polycarbonate that was part of the motivation for the
rebuild. To reduce the chances of severe damage, the
walls were designed to have easily replaceable, smaller,
and better protected polycarbonate walls. This was
done through two design features.

First, the arena has a four inch tall shock mounted
steel bumper along the floor that keeps most weapons
away from the polycarbonate. Second, the
polycarbonate is slotted into extruded framing which
means that there are no sharp corners or stress
concentration areas. This also means that the